Analysing Non-Markovian Open Quantum Systems to Understand the Role of the External Environment in Cryptochrome-Based Magnetoreception

分析非马尔可夫开放量子系统以了解外部环境在基于隐花色素的磁接收中的作用

• 批准号: 2693369
• 金额: --
• 依托单位: UNIVERSITY OF EXETER
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2693369
• 关键词: Analysing; Non; Markovian; Open; Quantum

Magnetoreception, the ability of some animals to sense the geomagnetic field, has been a topic of considerable intrigue within the scientific community. Four decades of extensive research have demonstrate unequivocally that the extraordinary ability of migratory birds to navigate is supported by a visual 'magnetic compass'. It is now widely accepted that cryptochromes, a type of flavoprotein within the retinae of migratory birds, are responsible for facilitating this 'sixth sense'. Within cryptochromes, a radical pair is thought to be generated by photoactivation, the quantum coherent spin dynamics of which render the radical pair's subsequent recombination sensitive to the inclination of the Earth's magnetic field.The majority of current models of the avian magnetic compass treat the spin dynamics of the cryptochrome in isolation. However, recent theoretical investigations and experimental studies of the protein's magnetosensitivity in vitro show that the response of an isolated cryptochrome to the geomagnetic fields is far too small to feasibly support navigation. We hypothesize that this 'interaction strength gap' could be understood, and resolved, in terms of interactions of the cryptochrome with its environment, i.e. its open-system nature. Conventionally, one might predict that the noisy biological environment would solely lead to coherence loss in the cryptochrome, thus destroy its sensitivity to the external field. However, our preliminary studies suggest that, counterintuitively, it seems as though the environment itself can reinforce the delicate spin coherences. Specifically, the system-bath interaction can be a source of non-Markovian behaviour, which, under certain conditions, can act as driver of the spin dynamics and enhance the coherence and sensitivity of the system. This is contrary to what is observed in most instances quantum-technological applications for which interactions with an external environment lead to coherence loss and suppression of quantum effects.This project aims to theoretically study the spin dynamics of radical systems subject to non-Markovian noise and driving as a result of their embedding in a biological environment. To this end, we will develop the tools to treat the open-system spin dynamics of realistically complex radical pair systems under conditions of non-Markovian coupling and driving. We will then apply these approaches to radical pair processes in cryptochrome and, in addition, biological radical processes outside of the cryptochrome realm, such as lipid peroxidation. Initial approaches will be based on the framework of the hierarchical equations of motion (HEOM), developed by Tanimura and Kubo, while large, more realistic models will later be realized based on wave function-based extensions to HEOM. Non-Markovian effects have not been previously studied in radical spin dynamics, but preliminary analysis suggests that they hold the key to deciphering magnetoreception. This project will provide the corresponding answer, with far-reaching applications, e.g. for the development biomimetic quantum technology, and implications as to our understanding of quantum effects underpinning biological function.

磁感受，即某些动物感知地磁场的能力，一直是科学界相当感兴趣的话题。四十年的广泛研究已经明确表明，候鸟非凡的导航能力是由视觉“磁罗盘”支持的。现在人们普遍认为，隐花色素是候鸟视网膜中的一种黄素蛋白，负责促进这种“第六感”。在隐花色素中，一对自由基被认为是通过光活化产生的，量子相干自旋动力学使得自由基对随后的重组对地球磁场的倾斜敏感。目前大多数鸟类磁罗盘模型都将隐花色素的自旋动力学孤立地对待。然而，最近的理论研究和实验研究的蛋白质的磁敏感性在体外表明，一个孤立的隐花色素的地磁场的响应是太小，可行的支持导航。我们假设，这种“相互作用强度差距”可以理解，并解决，在隐花色素与其环境的相互作用，即其开放系统的性质。传统上，人们可能会预测，嘈杂的生物环境只会导致隐花色素的相干性损失，从而破坏其对外场的敏感性。然而，我们的初步研究表明，与直觉相反，环境本身似乎可以加强微妙的自旋凝聚力。具体而言，系统浴相互作用可以是非马尔可夫行为的来源，在某些条件下，可以充当自旋动力学的驱动器，并增强系统的相干性和灵敏度。这与在大多数情况下观察到的量子技术应用相反，在量子技术应用中，与外部环境的相互作用会导致相干性损失和量子效应的抑制。本项目的目的是从理论上研究自由基系统的自旋动力学，该系统受到非马尔可夫噪声的影响，并因其嵌入生物环境而受到驱动。为此，我们将开发工具来处理非马尔可夫耦合和驱动条件下现实复杂的自由基对系统的开放系统自旋动力学。然后，我们将这些方法应用于隐花色素中的自由基对过程，此外，隐花色素领域之外的生物自由基过程，如脂质过氧化。最初的方法将基于由Tanimura和Kubo开发的分层运动方程（HEOM）的框架，而大型，更真实的模型将在以后基于HEOM的波函数扩展的基础上实现。非马尔可夫效应以前没有在自由基自旋动力学中研究过，但初步分析表明，它们是破译磁感受的关键。该项目将提供相应的答案，具有深远的应用，例如仿生量子技术的发展，以及对我们理解支撑生物功能的量子效应的影响。